feat(xo-web): create a backup job schedule selector

[MathieuRA]

Screenshot

New UI component that will be used for chaining backup jobs.

Description

Short explanation of this PR (feel free to re-use commit message)

Checklist

• Commit
  • Title follows commit conventions
  • Reference the relevant issue (Fixes #007, See xoa-support#42, See https://...)
  • If bug fix, add Introduced by
• Changelog
  • If visible by XOA users, add changelog entry
  • Update "Packages to release" in CHANGELOG.unreleased.md
• PR
  • If UI changes, add screenshots
  • If not finished or not tested, open as Draft

[julien-f]

I don't think we should merge this until the feature and its workflow has been validated by the team or the product owner.

[julien-f]

I'm not fond of merging PRs before the code is really used.

IMHO, we should have continue working on this in this branch and then merge when the feature is complete.